Clutch operating mechanism



o. 9 .1945- L. H. SMITH V 2,386,512

CLUTCH OPERATING MECHANISM Filed April 2, '1945 2 sheets-sheet 1 OC- 9, 1945.- L. H. SMITH CLUTGH OPERATING MEGHANISM Filed April 2, 1943 `2. Sheets-Sheet 2 l Y Y yPatented Oct. 9, 17945' My nvention relates` to improvements vin clutch ,ope ting mechanismsjand haspar'ticular refer- ,QIIfQQ tu.. ,an ,improved, pneumatically' controlled rI r'ie'chanisnfi f oractuating 'the clutch of motor rvehicles '.thefprincipal-objects ofniyinvention lsgto .provide a` pneumatic Yopera tingfmechanism l for throwing the' clutchmechanisrn into or out .,Qf Opration@ Vv vhigcrrthe admissronefair under ,t retient-pray. mention is tofprovide a innglgglg 9,. power' operatedrnechanism for operating ythe' clutch, which will relieve the operator of theftiresome eiortresulting from the'manual Y ,fiperaonrf the 011111.10114. .n

ther` V'objects ofhlny invention ywill .appear hereinafter; l.. j 1 Referring to the accompanying drawings, which yillustrate one embodiment of theinvention,v

A Fig l is apla'n View of the throw-.out shaft of a clutch mechanismand the pneumatically oper- 'ated Icylinder and vpistoni `mechanism connected 'withjsaid kthrow-out shaft for operating the same; Fig. 2 is a verticalsection'substantiallyon the 7line 2 -2 of Eig. 1,'toget11r with a sectional view of the throttle or metering valve l,for controlling tliiegflow of 'airj'under pressure to throwdnv the cylinder; c

l1 i' g. 3 lis a sectional vievsnof a yconventional type 'Lof clutch usedfin'rnotor vehicles `for connecting andfdisconnecting the motor with' respect tothe transmission mechanism'of the vehicle; and

Fig. 4'is a sectionalview of Ya modicatin of th e m echanisr n shown irifFi'gs'. land 2.4 Referring rst to Fig. 3,"there is shown in sectiona clutchv Afoffthefusual or conventional' type in which a 'clutch plate I is carried upon a driven shaft `2 and isV r` ositioriedv between driving plates 3 carried-by the flywheelof the motor 4 and a Vclamping member 5. AWhen theseY plates are clamped together, the coupling or driving connec'tin between 'the' motor vand the driven mechanism-of the-vehicle is established and the clutch isv said? to be infor' vrclosed.y Conversely, when the `d rivin'g'and drivenplatesare relieved of clamping 'pressure' andsIightly separated; if the driving plates can rotatewith the moto`rindependent1y rof the driven plate andthe clutch' is said to be Ingthe usualtype :of clutch'such 'as shown in IigQ-S,` the clamping member 5 isjpivotally connectedat 6 to a series of levers 1 -wh'ich'are fulf PATENT OFFICE OPERATINGMECHANSM f-Lawrence n. smith, chicago, 111.; assigner to General American.'.Aerocoach'CompanL -Ill., a corporation ofDelaware- Applicatiprifapril g, 1943, serial Na 481,547, .solaima (er 19g-'9pm Chicago,

crumed onV` relatively fixed mountings 8. These levers converge radially to a bearing Sjwhich is carried by aI-sleeve III` movable longitudinally on Y asupport surrounding' the driven shaft 2,' so vthat when'the-sleeve I0 isshifted to the left in Fig. 3, it swingsjthe levers I about Vtheir fulcrums and carries .the-clamping member 5 away from the clutch plates, thus opening or throwing out the clutch.` This clamping member, however, is'norm'ally 'clamped against the plates by means of a lseries of springs II, so thatthe clutch is norrnallyfclosed..4 Thus, in opening or throwingvout the clutch, the power .or force applied to the sleeve I0 must be suflicient to overcome pressure of the springs II v'on the clamping member.

Power ,is applied" to the shiftable sleeve I0 through ya clutch throw-out shaft I2, which carriesngers I3 .adapted to bear'against lugs or vears I 5On.thesleeve I0, Thus when the shaft yI2 yis rotated in its bearings in one direction by power applied thereto, itv shifts the sleeve and opens the .,clutc'h; and when the pressure or power on the 4 s haftfisj relieved, the clutch springsY II, acting throughthe levers 1 oi. the clutch, rotate the shaft in theopposite direction and restores itto normal position.

In thev operation ,of the clutch,the throwing or letting in of the clutch-must be done somewhat 'gra'dually, 4 s o that some rslippage between the jplates willoccury until the vehicle has gotten under way otherwise, the powerv of the motor is too suddenly lappliedto the' driven shaftof the vehicle andthe clutch is said to grab. When the Ytlircyw-(Jiltshaft`of the clutch is operated by a foot treadle, the grabbing of the clutch is avoided Y bythe operator easing back on 'the foot treadle v*until the vehicle has picked up in speed.

. Aira'cftuated mechanism has been proposed for operating the throw-outv shaft in place'of the manual foot treadle, but this mechanism has usually 'consisted of apiston and'cylinder into whichfcompressed air is admitted to throw the 1clutch out'cr open; and froniwhich the air is exhausted to let the clutch in. Theseldevices have not been successful, however, because it is almost'impossible to control the emission or exhaustion of air fromthe device in a manner which will allowthe proper easing inV of the clutch.

1 'l'n'accordance with' my invention, however, I oyercorrie this difficulty byr gradually'building .anism can beffcontrolledvery accurately and lsuitable type for the. purpose.

acts very smoothly in gradually throwing in the clutch.

As shown more particularly in Figs. 1 and 2, the outer end of the clutch throw-out or rock shaft I2 is provided with an upstanding arm 20.`

justment purposes. The forked ends are pivotally connected at 30 and 3| respectively to the throwout shaft arm 25. Each piston is provided with a stop member 32 which bears; against the cylinder head and acts as a limit stop to determine the range of movement of the arm 20. Sincethe pivotal connections of -the pistons to the arm 2li` move in an arc, the cylinders are pivotallymountedat 33- and 34 on suitable brackets 3 5 Yand 36 whichv are mounted on theclutch housingV 31 and transmission housing 38 respectively. l

TheV cylinders are opposed to eachother so far as the application of power to the arm 20 is concerned. The cylinder 22which I termthe throwout cylinder, is directly connected by pipe 39 to a source of compressed air `of preferably constant pressure, such as the compressed air tank employed on motor vehicles for airbrake and other operations. The piston of cylinder 22 is thus subljevct to constant pressure and the parts are so proportioned `that the power applied to` arm 20 if unopposed. is sufficient toovercome the spring mechanism ofthe clutch and throw out and hold out the clutch.` l Y Thecylinder 2|, which. I term for convenience the. throw-in cylinder, is likewise connected, by means of pipes 4|) and 4|, to said source oi compressedv air through a controlvalve B by means of which the admission of air. to. and` the exhaustion of` air from cylinder 2|` is controlled. The power applied to arm 20 bythe piston` of cylinder` 2| is opposite to that of cylinder 22, and

the parts are so proportioned that its' applied power can be substantially equal to that of. cylinder 22..

Themetering or control valve B maybe` of any The valve shown in Fig. 2 is of atype now in usefor air-flowcontrol.v It is provided with two chambers 42 and 4 3 Chamber 4.2 is connected by pipe 4| to the throw-inf cylinder .2| and chamber 43 exhausts to the atmosphere through pipe. 44. The flowA of -air'to and from this` chamber 42, and hence the cylinder 2|., is controlled lby the valve 45` which has two valve-:members on the same stem. The .valve member 46iwhen not seated admits air under pressure from the source 4I] to cylinder 2|. The valve member 41 seats on the end of the hollow stem 48which moves up and down in respense to the `foot treadle 423.` The'foot treadle is ulcrumed at l58 in convenient position for the operator andits toe end is normally urged upwardly by a spring 5|.` Its heel end bears upon and normally holds depressed the valve stem 48S` against a spring 53fin the valve which urges thestem upwardly.

Normally the; metering valve is in position shown in Fig. 2 in which the valve member 45 is open and pressure is admitted to the cylinder 2|. Pressure in cylinder 2 opposes that in the throwout vcylinder 22 with the result that the arm 20 is not actuated and the spring means yof the clutchA maintains the clutchclosed.

When the operator depresses the treadle, the hollow stem 48 rises and is followed by stem 45 until valve member 46 seats and closes the flow of air to the cylinder 2|. Continued rise of stem 48 lifts the stem from valve member 41 thus opening chamber 42 to the atmosphere and exhausting pressure from cylinder 2|. Exhaustion of pressure from cylinder 2| thus relieves the, throwoutcylind'er22v of opposition and `allows it to apply power to the arm.v 20 and* overcome the spring mechanism of the clutchv to throw the clutch out quickly and positively. So long as the operator maintains this condition of the control valve, the clutch will be held out.

' WhenA the clutch is to be thrown in, the operator eases back on the foot treadle which depresses' the valve stem 48 and causes irst the valve member 41 tovclose the exhaust valve and the valve member 46 to open communication from the air pressure source to the throw-in cylin der 2 l. This builds up pressure in said cylinder until it lovercomes the action of. the throw-out cylinder and. allows the spring `mechanism of the clutch to restore the clutch to in position. Since the cylinder 2 I' is acting yin the same direction as the spring mechanism of the clutch, the pressure buildingjup inthe cylinder 2| need onlybe equal 'to the pressure dierential betweenV the throwout cylinder and the spring mechanism. of the clutch. The building-up pressure in the throwin cylinder isy thus acting against the constant pressure ofV cylinder 22 and'` as. a. balance is reached between the building-up pressure. andthe differential pressure between the clutch spring -mechanismand the throw-out cylinden.. the

clutch springy mechanism is gradually allowed to smoothly let inthe clutch.

In the present structure, the cylinders are, preferably of equal diameter and when,. as shown in Fig. 2, both cylinders are under full pressure from the` source,A they both. apply substantially equal power to the arm-.20.. It, is desirable. however` in clutch operatoato insure. that` the clutch levers 'l are actually slightly out, of contact with bearing. El when the clutch. is in for the purpose of preventing undue wear on these parts. For vthis reason I havey arranged, the mechanism so as to give the throw-in cylinder 2| a slight mechanical advantage over the throw-out. cylinder by connecting the pistons thereof on` diierent radii to the arm 20. The pivotal connection 3|!` of the throw-inrpiston is. on a longer radius Vthanthe `connection 3| of thethrow-outpiston. Thus. the

power applied to the arm 2li by the throw-in cylinder will,preponderateslightly over` that applied'by the throw-out cylinder .and will insure the fingers |3. being positively held out@ l InFigA-I have illustrateda modification of the mechanism in which a spring. 55v is utilized instead `of the air-operated throw-out cylinder and in'wffhich the functions of bothv cylinders are combined in a-vsinglcY device. The cylinder 56 corresponds to the .throw-in. cylinder A2:| and. is providedwithapiston 23, and a piston rod. 25, pivotally connected in the same, manner tothe arm 20. The spring 55 is positionedbetween the` piston and the cylinder head and acts von-the ypiston/,and hence the arm 26 in the same direction as cylinder 22. The spring, 55. is proportioned tol apply suilicient` power` toV overcomev the spring mechanism of the: clutch` in the samemanner as that applied by the cylinder 22. The throw-in cylinder isy connected to thev control valve and is controlled thereby in the same manner as vhereinbe.- foredescribed. Y

I claim:

1. In a mechanism for operating a clutch having spring means therein normally holding the clutch closed, the combination of a source of air under pressure, a clutch opening pneumatic device comprising a cylinder and piston therein connected tosaid source of air pressure and normally acting to overcome the spring means of the clutch to open the clutch, -and a pneumatic device opposing the action of the opening device when air under pressure is admitted thereto.

2. The combination of a clutch having spring mechanism normally holding said clutch in and having a rock shaft for actuating said spring mechanism to throw the clutch in or out, a source of air under pressure, a pair of cylinders and pistons therein connected in opposed relation to said rock shaft, one of said cylinders being conadjacent the clutch and having pistons pivotally connected to said arm, one of said pistons being constantly subject to air under pressure, a treadle, and a valve actuated by said treadle to vary the air pressure in said other cylinder.

` LAWRENCE I-I. SMITH. 

